Summary of Key Points WHO Position Paper on Vaccines against Hepatitis E Virus(HEV) May 2015 1
Background l Hepatitis E Virus (HEV): leading cause of acute viral hepatitis in developing countries. l Genotypes 1 and 2: Primarily infect humans, mainly male young adults Annually cause 20.1 M infections, 3.4 M symptomatic cases, 70 000 deaths, 3000 stillbirths. Genotype 1 is: most prevalent; widely found in Asia and Africa; causes high mortality in pregnant women, and poor fetal outcomes Genotype 2 cases in Mexico, Nigeria, Namibia l Genotypes 3 and 4: Primarily infect mammalian animals; occasional transmission to humans Genotype 3 cases almost entirely in developing countries Genotype 4 human cases mainly in mainland China and Taiwan 2
Background l HEV transmission: Sporadic disease in endemic countries. Periodic large epidemics due to contamination of water sources. Greatest disease burden in developing areas where clean water is scarce. l Treatment: There are no WHO guidelines on treatment of Hepatitis E. Treatment is generally supportive. 3
Vaccines l HEV 239 Vaccine: Hecolin Experimental vaccine at clinical trial stage in humans that has been developed and manufactured. Currently only licensed in China Licensed for use in people 16-65 years of age who are at high risk for HEV infection based on occupation/lifestyle Those involved in animal husbandry, food handling, students, army personnel, young women, travellers 4
Immunogenicity and Effectiveness l Highly immunogenic Almost all recipients seroconverted after 3 doses on a 0,1,6 month schedule. l Efficacy rate: High efficacy rate in healthy adults between 16-65 years of age in China, primarily against Genotype 4. Limited data on protection against Genotype 1 No data on protection against Genotypes 2 and 3 However, there is data to show expected protection against all 4 genotypes. 5
WHO Position l Hepatitis E recognized as an important public health problem in developing countries Especially among special populations: pregnant women, displaced individuals living in camps, outbreak situations. l In the absence of sufficient information, the WHO does not: make a recommendation on the introduction of the vaccine for routine use in national programmes in populations where epidemic and sporadic hepatitis E disease is common. However, national authorities may decide to use the vaccine based on the local epidemiology. Recommend routine use of vaccine in the following groups in endemic areas: Children below age of 16 years Pregnant women Patients with chronic liver disease Patients on organ transplant wait lists Travellers 6
WHO Position l In outbreak situations (high risk of Hep E) WHO recommends: Considering use of HEV 239 vaccine to mitigate risk of Hep E outbreaks for high risk groups: Pregnant women Travellers Health and humanitarian relief workers Evaluate risk and benefit of vaccination on an individual basis l To address information gaps WHO recommends: Pre-emptive design of research protocol to study vaccine safety and immunogenicity in outbreak situations among high risk groups. 7
Information Gaps l Incidence and mortality of the Hep E disease in general and in special populations; l Immunogenicity of HEV 239: outside the 16-65 age range in populations at higher risk for hep E disease E.g. with pre-existing liver disease or immunosuppressive conditions in pregnant women after SC vs. ID administration on an accelerated schedule. 8
Information Gaps l Efficacy of HEV 239: against disease caused by genotypes 1, 2 and 3; long term efficacy, duration of protection with fewer than 3 doses or shorter intervals between doses; need and timing of potential booster dose l Effectiveness of HEV 239 l Cost effectiveness of vaccine programme in outbreak settings 9
For more information on the WHO HEV position paper, please visit the WHO website: www.who.int/immunization/documents/ positionpapers